Growth of ZnO nanostructures by vapor–liquid–solid method

Applied Surface Science

et al. 2010

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113

The surface composition of as-grown and annealed ZnO nanorods arrays (ZNAs) grown by a two-steps chemical bath deposition method has been investigated by Xray photoelectron spectroscopy (XPS). XPS confirms the presence of OH bonds and specific chemisorbed oxygen on the surface of ZNAs, as well as H bonds on 0) 1 (10 surfaces which has been first time observed in the XPS spectra. The experimental results indicated that the OH and H bonds play the dominant role in facilitating surface recombination but specific chemisorbed oxygen also likely affect the surface recombination. Annealing can largely remove the OH and H bonds and transform the composition of the other chemisorbed oxygen at the surface to more closely resemble that of high temperature grown ZNAs, all of which suppresses surface recombination according to time-resolved photoluminescence measurements.

Section: Resultsmentioning

confidence: 99%

Origin of the surface recombination centers in ZnO nanorods arrays by X-ray photoelectron spectroscopy

Applied Surface Science

et al. 2010

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113

“…During the past decade, different one-dimensional ͑1D͒ ZnO nanostructures such as nanotubes, 1 nanowires, 2 nanorods, 3 nanobelts, 4 nanocables, 5 and nanoribbons, 6 have been successfully fabricated by different methods. Among the methods to prepare 1D ZnO nanorods, [7][8][9][10][11][12][13] chemical bath deposition ͑CBD͒ appears to have a huge potential for industrial synthesis due to advantages such as easy operation and low temperature fabrication. 14,15 Recently, we successfully controlled the size of well-aligned ZnO nanorod arrays ͑ZNAs͒ from 40 to 150 nm with the two-step CBD method, 16 i.e., by first spin coating the substrate with a seed layer of ZnO nanoparticles and then using the CBD growth.…”

Section: Introductionmentioning

confidence: 99%

Annealing effects on optical properties of low temperature grown ZnO nanorod arrays

Journal of Applied Physics

et al. 2009

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129

Vertically well-aligned ZnO nanorods on Si substrates were prepared by a two-step chemical bath deposition method. The structure and optical properties of the grown ZnO nanorods were investigated by Raman and photoluminescence spectroscopy. The results showed that after an annealing treatment at around 500°C in air atmosphere, the crystal structure and optical properties became much better due to the decrease in surface defects. The resonant Raman measurements excited by 351.1 nm not only revealed that the surface defects play a significant role in the as-grown sample, which was supported by low temperature time-resolved photoluminescence measurements, but also suggested that the strong intensity increase in some Raman scatterings was due to both outgoing resonant Raman scattering effect and deep level defect scattering contribution for ZnO nanorods annealed from 500 to 700°C.

“…Among various 1D nanostructural materials, Zinc oxide (ZnO) has generated great interests due to its direct wide band gap of 3.37eV at room temperature, large exciton binding energy of 60meV, and stable physical and chemical properties. Until now, different fabrication methods, such as vapor-phase transport [7][8][9], pulsed laser deposition [10], chemical vapor deposition [11,12] and electrochemical deposition [13], have been widely reported for the preparation of 1-D ZnO nanorods. According to these methods, the complex processes, sophisticated equipment and high temperatures are usually required.…”

Section: Introductionmentioning

confidence: 99%

Effective way to control the size of well-aligned ZnO nanorod arrays with two-step chemical bath deposition

Journal of Crystal Growth

et al. 2009

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The diameter of well-aligned ZnO nanorod arrays (ZNAs) grown on Si substrates has been well controlled from 150nm to 40nm by two-step chemical bath deposition method (CBD), i.e. substrate pretreatment with spin coating to form ZnO nanoparticles seed layer and CBD growth. The effects of ZnO nanoparticles density and diameter on size and alignment of ZNAs were investigated in detail by atomic force microscope (AFM), X-ray diffraction (XRD), scan electronic microscope (SEM), transmission electron microscope (TEM) and photoluminescence (PL). The results indicate that both diameter and density of ZnO nanoparticles which were pre-coated on the substrates will influence the size and alignment of ZNAs, but the density will play a key role to determine the diameter of ZNAs when the density is higher than the value of 2.3×10 8 cm -2 . Moreover, only a strong UV peak at 385 nm appears in room temperature PL spectrum for these samples, which indicates that as-synthesized ZnO nanorods have a perfect crystallization and low density of deep level defects.